Alpine R-Series R2-W12D2 12 Inch Dual 2-Ohm Voice Coils Subwoofer with 750W RMS
Amazon.com: Alpine R-W12D4 Car Audio Type R Series Sub Dual 4 Ohm 2250W Peak 12" Subwoofer and HA-SWKD Dual Subwoofer Sub Box Install Kit : Electronics
Alpine R-Series RS-W12D4 12" Shallow Mount Subwoofer with Dual 4-Ohm Voice Coils
Alpine SWR-1221D 12" Dual 2-ohm Voice Coil Subwoofer at Crutchfield